1. Avoiding getting contacted by WLM:
Go to "Options > Privacy" and enable "Only people in my Contact List can see my status..."
2. Avoiding getting contacted by Mail:
Go to
http://mail.live.com/ , sign in, go to "Options (Click Options, then click More Options...) > (Junk e-mail) Safe and blocked senders > Blocked Senders" and add his e-mail to the blocked senders list.
Screenshot of blocked senders page.
After that, he won't be able to contact you at your Live ID. Other mail providers offer such funcionality too.